This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light and not as admissions of prior art.
In conventional drilling operations, a string of drill pipe or other drilling tubular is lowered into a wellbore. The lower end of the drill string typically includes a bottom hole assembly (BHA), which features a drill bit that can be rotated to cut into the subterranean formation to advance the wellbore through the formation. Some existing systems utilize a downhole drilling motor that is part of the BHA to rotate the drill bit.
Downhole drilling motors include a drive shaft that may be coupled to the drill bit to rotate the drill bit at a desired rate. The drive shaft is located inside a housing and designed to rotate with respect to the housing. A power section located upstream of the drive shaft may transmit the driving power needed to rotate the drive shaft. Conventional drilling motors are designed and manufactured with thrust bearings to carry both bit weight load and hydraulic load created by pumping fluid through the power-section. These bearings are generally located in a lower section of the tool assembly known as the bearing pack. To accommodate this arrangement, the hydraulic load from the power-section is translated through a transmission coupling located between the bearing pack and the power-section.
Conventional transmission couplings are often designed as universal joints that only translate torque. Unfortunately, additional compression loads can be placed on the mud motor transmission coupling, thereby causing the coupling to rotate while in a bind. This arrangement can cause premature wear, undesirable “ring out” conditions, and rough or cogging rotation movement within the joint. This may lead the transmission coupling to utilize more torque from the power-section to translate a desired amount of torque to the bearing pack shaft, thus yielding a less efficient motor assembly.